1. Field of the Invention
Aspects of the present invention relate to a rechargeable battery. More particularly, aspects of the present invention relate to a rechargeable battery having an improved core structure disposed in an electrode assembly.
2. Description of the Related Art
A rechargeable battery can be discharged in use and recharged, unlike a primary battery that cannot be recharged. A low-capacity rechargeable battery is formed of one cell. Low-capacity rechargeable batteries have been used for portable small electronic devices such as mobile phones, laptop computers and camcorders. A large capacity rechargeable battery includes a plurality of cells that are connected in a form of a pack. Large capacity rechargeable batteries have been widely used as power sources for driving, as an example, the electric motor of a hybrid electric vehicle.
Rechargeable batteries been manufactured in various shapes. Representative shapes thereof are a cylindrical shape and a square shape. Rechargeable batteries are connected in series to form a large capacity rechargeable battery module in order to drive the motor of an electric vehicle or the electric motor of a hybrid electric vehicle, both requiring a large amount of electric power.
A rechargeable battery internally includes an electrode assembly having an anode and a cathode with a separator interposed, a case providing a space for housing the electrode assembly, and a cap assembly for closing and sealing the case.
The anode and the cathode are formed in a belt shape that extends in one direction, and include an uncoated part at one end in the length direction. The uncoated part is a part that is not coated with an active material.
The electrode assembly is spiral-wound around a core of a cylinder shape with the separator interposed between the anode and the cathode. That is, the electrode assembly basically forms a cylinder shape. Here, the anode uncoated part and the cathode uncoated part are disposed to face different directions. The core not only supports the electrode assembly in a winding process, but also sustains the shape of the spiral-wound electrode assembly.
The cathode uncoated part includes a cathode current collector plate, and the anode uncoated part includes an anode current collector plate. The cathode current collector plate is electrically connected to the case, and the anode current collector plate is electrically connected to the cap assembly, thereby providing current to the outside.
As the rechargeable battery is charged and discharged repeatedly, the electrode assembly gradually expands. Accordingly, stress between the electrode assembly and the case and between the electrode assembly and the core increases. Since there is generally enough margin space between the case and the electrode assembly, there is no great stress generated therebetween. However, comparatively large stress is generated between the electrode assembly and the core because there is no margin space therebetween.
If stress is concentrated between the electrode assembly and the core, the output of the rechargeable battery is reduced because charging and discharging efficiency deteriorates. Also, the life-span of a part with concentrated stress deteriorates and unstable reaction is thereby generated. Therefore, the life-span of the rechargeable battery is reduced due to the unstable reaction.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.